Inlet screen segment



y 1956 J. R. FOLEY 2,747,685

INLET SCREEN SEGMENT Filed Jan. 12, 1954 F/GJ lNl/ENTOR JOHN R,

ATTORNEY INLET SCREEN SEGMENT JohnR. Foley, Manchester, Cnn., a'ssignor to "United AircraftCorporation, East Hartford, Guam, :1 corporationof Delaware Application January 12, 1954, SerialNo. 403,510

4 Claims. (Cl. 183-51) This invention relates to an inlet-screen construction for useespecially in a jetengine, for example, a gas tur bine power plant, to prevent the entrance of foreign 'matter that might damage the engine. A screen construction of this type may be used, for example, in the air inlet screen of the Newcomb Patent 2,618,358.

: The principal feature of the invention is a screen construction which presents a minimum of obstruction to the air flow but which-has high strength and stoppage ability. One feature of the invention is a screenmade up of a series of closely spaced streamlined flat strips placed edgewise to the air flow and braced by smaller strips crossing the streamlined strips at more widely spaced intervals. Another'feature is the positioning of "the-screen so that the closely spaced strips-have a sWe'epback' with respect to the air flow.

Other objects and advantages will b'ejapparent from the specification and claims and from the accompanying drawings 'which"illnstrate an embodiment of the invention.

Fig. 1 is a plan View of a segment forming a portion of the inlet screen for the gas turbine inlet.

Fig. 2 is a sectional view substantially along the line of 22 of Fig. 1.

Fig. 3 is a sectional view showing one of the smaller spacing bars substantially along line 33 of Fig. 1.

Fig. 4 is a sectional View of the larger streamlined strips substantially along the line 4-4 of Fig. 2.

The invention is shown in the form of a segment of a screen for the inlet to a gas turbine power plant. This segment as will be apparent, is duplicated by other segments placed edgewise against the segment shown to form a complete annulus of segments which would fill the annular inlet to the power plant. Thus, for example, the screen shown would constitute one of the segments of the screen in the above mentioned Newcomb patent. The segments are adapted to be moved into and out of operative position by any well known mechanism, as for example, the mechanism of this Newcomb patent.

The inlet screen segment is made up of a large number of parallel streamlined strips 2, the spacing of which would be approximately five or six times the thickness of the strip itself. For example, each strip, the cross section of which is best shown in Fig. 4, may be approximately 5 hundredths of an inch in thickness and the spacing of the strip might be between 25 hundredths to 30 hundredths of an inch. When the segments are positioned in the power plant the direction of these strips is generally radial.

As shown in Fig. 4 these strips 2 preferably have a rounded leading edge 4 and an approximately sharp trailing edge 6. The opposite side surfaces 7 are shown as parallel rearwardly of the leading edge 4, and then converging to the trailing edge.

For the purpose of holding the bars 2 in parallel spaced relation to each other the screen has smaller strips 8 which extend in a direction generally at right angles to the strips 2. As shown in Fig. 1 these strips preferably extend. in a circumferential direction with respect to the gas turbine inlet and are preferably parallel to each other. These smaller strips arereceived in notches '10 in the 'leading edges of the strips 2, these notches being deep enough so that the leading edge of the smaller strips is in approximately the plane of: the leading edge of the larger strips 2. The strips 2 and 8 aresuitably welded together attheir junctions as by welding orbrazing.

The smallerstrips are preferably substantially shorter in cross'sectionin the direction of the :air flow than the larger strips 2. For example, as-shown in Fig. 3, the smaller strip 8 is approximately. one quarter of an inch long in cross section, andthe larger strip approximately one half of an inch long in cross section. The smaller strips are streamlined as shown in Fig. 3 and are substantially fiat having relatively sharp leading edges 12 and trailing-edges 14. In the particular arrangement shown the maximum thickness of thestrip 8 is'approximately thirty-five thousandths of an inch with the spacing' of thestrips 8 as widely apart as possible and still provide the desired stiffness and stoppage ability. In the arrangement shown the strips 8 are more than an inch apart.

has been found advantageous in a number of cases to have the screen extend'at other than a precise right angle to the direction of air flow. It-will be apparent that the notches lll are formed in'the strips 2 in such a manner as to assure that the strips 8 when positioned in the notches will have their maximum chordwise dimension parallel to the direction of the flow.

It has been found that a screeen of this type provides the required screening ability with a minimum of flow blockage and accordingly with a minimum of pressure drop in the air flow through the screen.

The individual screen segments may be reinforced by providing an outer plate 18 and a shorter inner plate 20 providing a connection between the ends of the larger bars or strips 2. These strips are curved to define the inner and outer curved walls of the screen segment. In addition, radially extending closure strips 22 may be provided at opposite sides of the screen segment thereby providing for a support of the ends of the smaller strips 8 and for the larger strips 2 which do not contact the inner plate 20. Where the strips 22 are provided they preferably extend forwardly of the general plane of the screen as indicated in the dotted line of Fig. 2 and similar strips 24 and 26 may then be provided along the inner and outer edges of the screen also projecting forwardly of the general plane of the leading edges of the screen. These strips 22, 24 and 26 form a forwardly projecting edge or boxing which prevents the escape of foreign matter collected on the screen, and retains the foreign matter on the screen during the moving of the latter from its operative position to the inoperative position out of the air inlet.

It is to be understood that the invention is not limited to the specific embodiment herein illustrated and described, but may be used in other ways without departure from its spirit as defined by the following claims.

I claim:

1. A screen for an air inlet for a jet engine, said screen including a series of streamlined closely-spaced fiat bars having arcuate leading edges and substantially sharp trailing edges, said flat bars being constructed to be placed edgewise to the air flow, the cross-sectional length of said bars being substantially 10 times the cross-sectional width, said bars being spaced apart a distance approximately 5 to 6 times the thickness of the bars, and a second series of smaller streamlined bars extending substantially at right angles to said first bars for bracing them, the bars of said second series being much more widely spaced than those of the first series, said first bars having notches at an acute angle to, and extending rearwardly from, the leading edge to receive said second bars, said second bars being substantially onehalf the cross-sectional length of said first bars.

2. A screen for an air inlet for a jet engine, said screen including a series of streamlined closely-spaced flat bars having arcuate leading edges and substantially sharp trailing edges, said fiat bars being constructed to be placed edgewise to the air flow, the cross-sectional length of said bars being substantially 10 times the cross-sectional width, said bars being spaced apart a distance approximately 5 to 6 times the thickness of the bars, and a second series of smaller streamlined bars extending substantially at right angles to said first bars for bracing them, the bars of said second series being much more widely spaced than those of the first series, said first bars having notches at an acute angle to, and extending rearwardly from, the leading edge to receive said second bars, said second bars being substantially one-half the cross-sectional length of said first bars, said first bars being notched deeply enough so that the leading edges of all the bars are in substantially the same plane.

3. A screen for an air inlet for a jet engine, said screen including a series of streamlined, closely-spaced, fiat bars placed edgewise to the airflow and with the leading edges of the bars extending at an acute angle to the direction of the air flow through the screen, said bars having arcuate leading edges and substantially sharp trailing edges and being spaced apart a distance approximately 5 to 6 times the thickness of the bars, the cross-sectional length of each of said bars being substantially ten times its width, and a second series of smaller streamlined bars extending substantially at right angles to said first bars, the bars of said second series being much more widely spaced than the bars of the first series, said first bars having notches in the leading edges to receive said second bars, said notches extending into the bars at an acute angle to the leading edge, said second bars being substantially onehalf the cross-sectional length of said first bars.

4. A screen for an air inlet for a jet engine, said screen including a series of streamlined, closely-spaced, fiat bars placed edgewise to the airflow and with the leading edges of the bars extending at an acute angle to the direction of the air flow through the screen, said bars having arcuate leading edges and substantially sharp trailing edges and being spaced apart a distance approximately 5 to 6 times the thickness of the bars, the cross-sectional length of each of said bars being substantially ten times its width, and a second series of smaller streamlined bars extending substantially at right angles to said first bars, the bars of said second series being much more widely spaced than the bars of the first series, said second bars being substantially one-half the cross-sectional length of the first bars, said first bars having notches to receive said second bars, the notches in said first bars being in the leading edges and extending into the bars at an acute angle to the leading edge, said notches having a depth equal to the cross-sectional length of said second bars such that the leading edges of all the bars are in substantially the same plane.

References Cited in the file of this patent UNITED STATES PATENTS 2,534,138 Marshall Dec. 12, 1950 2,546,153 De Remer Mar. 27, 1951 2,618,358 Newcomb Nov. 18, 1952 

